Acoustic horn



July 3, 1928. 1, 15,313

} M. AB'BAHAMS nmsnc 361m F110;! Sept. 13, 1926 2 Sheets-Sheet 1 mmmmm INVENTOR.

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BY fi w A TTORNEY July 3, 1928. 1,675,318

.M. .ABRAHAMS ACOUSTIC HORN Filed Sept. 13. 1926 2 Sheets-Sheet 2 IN VEN TOR.

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BY 5 d ATTORNEY 7 Patented July 3, 1928.

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ACOUSTIC HQRN.

e u ti n si mse temter 1a, 492 Serial Np.,1,;;5,214.

My invention .relates broadly to acoustic horns and more particularly ,to a constructionof an acoustic horn having a relatively long air column for the efficient reproduction of ;the entire range of ,musical notes encountered .in radio broadcast.reproduction.

One of the ,objegtsof ny invention .is to provide construction of spirally shaped acoustic horn haying a,. relatiuely long .air column on i vhich ,a sound generator is arranged to operate for the reproduction ,of musical notes orer a broad range of tone frequencies.

Anotherobjectpf my invention is .to v proyide a construction of spirally shaped a ustic .horn capableof .bei-ng moulded in sp al formation for providing .a rig d spirally shaped a1r colun1n,.the matei alcf the acoustic .horn being so formed asto have minimum tendency to Vibrato or otherwise undesirably modify the sou nd being amplifi d 7 Another object of my invention is to pro yide a flex ble skeleton frame, construction which maybe formed into .the shape ofa spiral forreproducing the over dimensions of a relatively and upon which naterial and hardened .for shaped aiizcohnnn. A

Another obj ect, of invention resides in the constructionof aspirallyshapedacoustic horn fOllhedby Windingajlexilile reed upon a. conical shaped mandrel and .irrapping the reed bod ithus Jformed with.liexiblelmaterial which is secured in' position ,thereover a-nd subsequently covered With additional layers ofmaterial Whiclrmay be impregnated with a hardener andthe mould lu'oundinto the shape desired and baked ,to harden in the final shape.

My invention \j 'lllbGzIllOlfQ clearlyunderstood from .the specification hereinafter following .by reference to the accompanying drawings in which:

Figure ;1 represents a mandrel on which the .fiexible skeleton frame ofiny invention (formed; Fig. ,2 shows reed partially .wound upon the mandrel; Fig. 3i1lustrates a layerof cloth partially Around over the reed with a cordor thread oundbetween the turns of the reed and. over the layer of cloth; Fig. 4 illustrates the flexible acoustic horn construction after it is removed from the mandrel and before it is wound into shape prior to the attachment of the bell at all. physical may be deposited for ning a rigid sp rally long air .column thread between the spaced turns tical Way .in which a long'aircolumn could be secured in anacoustichorn within small physical dimensions. The manufacture ofa horn of long aircolumn has heretofore been so .difiicult as ;to render ;the expense prohibitive for the practical manufacture of acoustic horns of spiral formation .on a quantity production basis.

;By 1 my present 'inyention I have devised a method of manufacturing an acoustic horn of any desired lcn gth which n ay be formed into a relatiyely small physical dimension fo s c ing .e l o h 'asliz mt -swu he acteristics of a long ,ai-rjcohnnn in the ren di en f .seii dev e W d range f 29 if eue eies- Referring tothegdrawings in more detail, reference character 1 represents a mandrel su antia y in th shap of a t u ca d cone on which the ihorn ;0fn1y invention is form d- .In Fig- 2 I have llu t a th construction of the horn of my invention wherein a fie xible reed ,or wire 2 wound upon t emand A th ndie th rmdrel here the dialneter is relatively small 1 .wind the ;turns of vthe reed close together between the sound, generator .and the horn as represented at 3 forming a connection in the natureofa rigid ferrule. Throughout the remainder of the lengthof the horn thereed 2 has its turns ,wound in spaced rele e ship a r p i entedet 41 p n 5 .where theturns arewound, closely-together. lheq s a acen twins at 3 an fi a c r in pe ti n ysm n .t=ipe-. l -Q other forms of, gum1ne d strips. Over the flexible reed skeleton form thus constructed I- in d a.stri p of cloth Ginspiral formation throughout thedengthof the reedform, and over this :strip of clothis wound a cordor 4 of the reed 2 in such manner that the cloth 6 is tightly stretched over the reed form of each of the turns of the'skeleton body. The air column thus formed consists of a long, flex ible cloth covered conical shaped horn having the appearance of a plurality of sections of gradually increasing diameters from a relatively small diameter to a relatively large diameter. The cloth 6 is tightly stretched over each of the turns of the reed 2 so thatthe appearance of the flexible horn from the side thereof is that'of a long series of semi-circular sections placed side by side throughout the length of the air column.

The flexible form as it is removed from the mandrelis shown in Fig. 4 ready for the process of bending into the final shapeand the securing of the bell 8 to the end thereof. Over the flexible form I Wind strips of cloth 9 Which are impregnated With a hardener and the horn ,body then ound 7 into the shape desired as represented more clearly in Fig. 7. A finishing coating is placed upon 'the fabric 9 as representedat 10 for ornamenting thesurface of the horn and securing a smooth finish throughout the length of the air column. 7 The horn may then be I baked or dried for the purpose of'hardening the horn in the final shape in Which it has been placed. The bell of the horn may be suitably finished and the entire body both inside and outside suitablydecorated. The particular form in Which the horn in its flexible condition is Wound may vary. The

spiral formation I have illustrated in Fig. 7 is only one of its possibleembodiments for I havealso formed the horn by coiling the flexible form in such manner that the ends of the horn are closely adjacent and the intermediate portion of the horn is Wrapped upon itself. fA variety of shapes; may be imparted to the horn for obtaining the long air column 'xvithin a small physical space, In this Way a relatively small cabinet structure may be employed for housing the acoustic horn. V

lVhere desirable the flexible reed may be removed after the horn is hardened or it may remain in the horn for the purpose of adding mechanical rigidity. By a process ofdipping the interior Walls of the horn maybe made smooth and the turns of they reed orthread so rigidly anchored by the construction lhave described that there is a minimum tendency forvibratory aetionof the walls of the acoustic horn and therefore substantially no interference ivith the am- 13lifi cation, "of sound emanating from the amplified sound at the hell 8. i The skeleton'frame is made 0 sound generator which is secured to theend 3 of the acoustic horn for delivery of the f prime round reed Whichis thepcore of the mean. The

material Whichcovers the skeleton frame may be; impregnated and hardened. in accordance with the principles set forth in my Letters Patent No. 1,501,032 on acoustic horns, dated July 15, 1924.

VVhile I have described my invention in one of its preferred embodiments I desire that it be understood that modifications may be made and that no limitations upon the invention are intended other than are imposed by the scope of the appended claims,

hat I claim as new and desire to secure by Letters Patent of the United States is as follows: V

1. An acoustic horn comprising a flexible skeleton frame, and an impregnated fabric covering for said first mentioned covering,

said skeleton frame being capable-of being.

coiled iii to the shape of a spiral.

'2. An acoustic horn comprising a flexible skeleton frame formed by a member having its turns closely positioned at its extreme skeleton frame, a cloth covering said flexible ends and more Widely spaced intermediate the ends, a'vvrapping of cloth for said skeleton frame, a thread Wound over said cloth and between the turnsof said skeleton frame intermediate the ends thereof for stretching said cloth over said mould, and an impregnated covering for said cloth Whereby'said skeleton frame may be coiled into compact space While obtaining an air column of relatively long length.

3. An acoustic horn comprising a flexible reed Wound into a plurality of successive convolutions; each of said convolutions gradually varying in diameter from a relatively small diameter at one end to a relatively large diameter at the other end, a strip of 7 material spirally Wound over said flexible reed and rigidly secured With respect to the convolutions thereof, the acoustic hornthus formed being coiled .lIltO spiral formation and a hardeningcoating for said horn for rigidly securing said horn in the form in which it is coiled.

4:. An acoustic horn comprising a flexible ,In testimony whereof I affix my signature.

MAX ABRAHAMS, 

